Probabilistic risk assessment of occupational exposure to respirable crystalline silica among ceramic workers in an industrial town in Iran: a Monte Carlo simulation approach

This study aimed to evaluate occupational exposure to respirable crystalline silica (RCS) and assess the lifetime cancer risk (ILCR) and non-cancer hazard quotient (HQ) among ceramic workers. A cross-sectional study was conducted across four occupational groups: polisher/washer, finisher, caster, and material handler. Personal air sampling was performed using NIOSH 7602 methodology to measure time-weighted average (TWA) RCS concentrations. ILCR and HQ were calculated using Monte Carlo simulation with 10,000 iterations, incorporating exposure parameters and health risk models from USEPA guidelines. The mean concentration of respirable crystalline silica (RCS) among workers exceeded both Iran OEL and threshold limit value (TLV) in all four occupational groups, with the highest level observed in Polishers (2.76 mg/m³). Monte Carlo simulation revealed that all groups had Incremental Lifetime Cancer Risk (ILCR) values above the acceptable threshold of 1.00E-06, with polishers showing the highest mean ILCR (5.66E-04). Similarly, Hazard Quotients (HQ) exceeded in all groups, indicating significant non-cancer health risks, particularly in Polishers (mean HQ = 114). These findings indicate a high probability of developing silica-related diseases such as silicosis and lung cancer, emphasizing the need for immediate control measures. The results demonstrate that ceramic workers are exposed to hazardous levels of respirable crystalline silica, posing serious long-term health risks. The use of Monte Carlo simulation provided robust estimates of both carcinogenic and non-carcinogenic risk, confirming the urgent need for regulatory enforcement, engineering controls, respiratory protection, and targeted health education to prevent silica-related diseases in this high-risk population.